Apparatus for use in the fire control of antiaircraft guns



235*405 fir Sept. 8, 1931. P. w. GRAY 1,821,968

APPARATUS FOR USE IN THE FIRE CONTROL OF ANTIAIRCRAFT GUNS Filed Feb. 14, 1925 Patented Sept. 8, 1931 UNITED STATES ATET OFFICE PERCY WILLIS GRAY, OF WESTMINSTER, ENGLAND, ASSIGNOR TO VICKERS LIMITED, OF WESTMINSTER, ENGLAND, A BRITISH COMPANY APPARATUS FOR USE IN THE FIRE CONTROL OF AN TIAIRORAFT GUNS Application filed February 14, 1925, Serial No. 9,180, and in Great Britain March 3, 1924.

This invention relates to apparatus for use in the fire control of anti-aircraft guns.

According to the invention the apparatus comprises a member which is moved in accordance with the rate of elevation (or the rate of training) necessary to keep an observing sight on the moving aerial target, or in accordance with this rate suitably modified by certain of the factors involved in the dem termination of the deflection, and another member which is associated with mechanism of such a character that when the latter member is caused to move at the same rate as the former member the vertical deflection (or the lateral or horizontal deflection) will be indicated and/or transmitted to the gun or guns. In the simplest aspect of the invention the said members are constituted by coaxial pointers of which one is angularly displaced positively by the elevating (or the training) handle of the observing sight and the other is angularly displaced through the intermediary of an infinitely variable speed device the adjustable element of which is set to a position causing'the second pointer to move at the same rate as the first pointer, by the conjoint operation of two handles or knobs acting through suitable multiplying mechanism. One of these handles is operated 30 in accordance with the time of flight of the shell and it follows therefore that the movement of the other handle is in accordance with the multiple of the rate of elevation (or the rate of training) and the time of flight, i. e. approximately in accordance with the vertical (or the lateral or horizontal) deflection. WVhen the apparatus is intended to determine both the vertical deflection and the lateral or horizontal deflection, a member moved in accordance with the time of flight factor is made common to the two portions of the apparatus dealing with the two deflections.

In order that the said invention may be effect, the same will now be described more fully with reference to the accompanying drawing which shows diagrammatically a form of apparatus in accordance with this invention.

clearly understood and readily carried into sin a cos a (1) Sin d=RE T sin a sin (a :l: d) o0sa (2) SmD RTXTX sin (1 (cos aid) where d=the deflection in the vertical plane.

R =the angular rate of elevation.

a=the present angle of site.

D=the lateral or horizontal deflection.

R =the angular rate of training.

T=the time of flight of the shell.

The said apparatus comprises an elevating telescope A and a training telescope A connected by a horizontal shaft B. This horizontal shaft is rotated by the elevating number in order to follow the target in elevation by means of an elevating handle I) and is supported in a bracket C rotated by the training number by means of a training handle 0 in order to follow the target in training.

B is a pointer operated by the elevating handle Z) through mechanism afterwards described and d is a concentrically mounted pointer operated by movement of a handle (1 (termed the vertical deflection handle) through mechanism afterwards described. C is a pointer operated by the training handle 0 through mechanism afterwards described and D is a concentrically mounted pointer operated by movement of a handle D (termed the lateral deflection handle) through mechanism also afterwards described.

The shaft B drives a number of shafts in accordance with its movements in causing the elevating telescope to follow the target in elevation; these shafts are indicated in the drawing by the reference character on as their angular movement is proportionate to the present angle of site on of the formulae. The handle d which as will be hereinafter shown is operated in accordance with sin (Z of Formula (1), drives two shafts d", 03 and the movements of one of the said shafts a and of the shaft 03 are added together by an epi- 100 tion to the aforesaid rod 1).

cyclic gear d which operates a shaft d in accordance with the sum of the two movements, i. e., in accordance with the factor (uisin (Z) which for practical purposes may be regarded as the equivalent of the factor (aid) of the formulae. If required, however, suitable means such as a sine cam or arm could be provided for eliminating the sine factor.

Rotation of the elevating handle I) rotates the primary element 6 of a variable speed device, which element is therefore rotated at a speed proportionate to the angular rate of elevating, i. e., proportionate to the factor R of Formula (1). The said Variable speed device may be of any desired construction and in the drawing is represented diagrammatically as of the kind in which the primary element 6 is in the form of a disc, the secondary element is in the form of a roller and the interposed element is in the form of balls mounted in an adjustable carrier 6 The said carrier is connected to a rod 6 which is slid to and fro in accordance with the changing values of Sin (aid) sin a by the linkage B which includes an arm b driven from one of the shafts on so that its angular movement is proportionate to the present angle of sight or.

right angles to each other by a block B which has a pin B disposed in a slot in onearm B of a bell-crank lever the other arm B of which is connected by a pin and slot connec- This linkage is for dividing a factor proportionate to the movement of the link B by a factor proportionate to the lateral movement of the link 6 and giving to the rod 6* a movement proportionate to the quotient, and as the link B receives from the arm B a lateral movement proportionate to sin (aid) and the link 6 receives from the arm 6 a movement proportionate to sin or, it follows that the rod 6 receives a movement proportionate to of the roller, this pointer is also rotated at a speed proportionate to the said factor.

The pointer (Z' is geared to the secondary element (F of a variable speed gear which, in the example shown, is of the kind in which the said element is in the form of a roller, the primary element is in the form of a disc 0Z and the interposed element is in the form of balls mounted in an adjustable carrier d. The said disc is driven by a constant speed motor rotating at a known speed (the driving gear being indicated at (5 and it follows that if the adjustable carrier d is so set that the speed of rotation of the pointer (l is equal to the speed of rotation of the pointer B then the travel of the carrier (Z measured from the centre-line of the disc, being proportionate to this speed, is a measure of the last-mentioned factor. The value of this factor is introduced by a rod (Z to a multiplying linkage d comprising a slotted pivoted arm (Z to which the rod (Z is connected by a pin and slot connection, a slotted slider d and a slotted bar 6 which is constrained to move in a path at right angles to the path of the slider (Z The members d cl and e are associated by means of a pin carried by a block slidably mounted on the arm d, this pin being disposed in the slots in the members d and e. The travel of the bar 6 is made pro portionate to the future time of flight of the projectile for which purpose it is adjusted through a screw and nut arrangement from a screw E rotated by a handle E This screw carries a nut having a pointer E arranged contiguous to a Height and fuse" chart E driven from the aforesaid shaft 6Z2 rotating in accordance with (aid). The said chart has two sets of curves, one for heigths and the v other for fuze numbers and the handle E is rotated so as to maintain the pointer E on the height curve corresponding to the particular height of the target. Consequently the bar 6 is moved in accordance with the future time of flight of the projectile and the fuze number can be ascertained from the particular fuze number curve indicated by the pointer E Alternatively the time of flight factor may be obtained by means of a threedimensional cam initially set for height and moved axially or radially in accordance with (a d), and similar means may be employed for obtaining the fuze numbers. It follows from the above considerations that the travel of the slider d is proportionate to sin (a d: d)

sin a R XTX From the aforesaid formulae it will be seen that the value of this factor increases or decreases by an amount SID 0i COS 0t and two cams F and G are provided from Whose rotation the values of D and sln a cos a are respectively obtained. The cam F is rotated from a shaft D operated by the aforesaid lateral deflection handle D and this cam bears against a pivoted arm f which is designed to move in accordance with The cam G is rotated from one of the shafts 0c and bears against a slotted slider g which is designed to move in accordance with sin a cos 0:. A pin on a block slidably mounted on the arm f asses through the slots in the slider g and a so through a slot in a slider H which is constrained to move in a path at right angles to the slider g. The members f, g and H (indicated generally by the reference letter F") serve to move the slider H in accordance with the factor Y Sin a COS oz- This slider operates a bell-crank lever h which is pivoted to a carrier (Z and is connected to so as to move a second slider (Z mounted in this carrier and the resultant travel of the latter slider thus becomes proportionate to i. e. proportionate to sin (Z (see Formula (1) The carrier (Z is operated by a screw on the aforesaid shaft (Z operated by the vertical deflection handle cl. It therefore follows that if the handle (Z is operated so as to cause the pointer d to move at the same rate as the pointer 13 the rotation of this handle is propol-tionate to sin d the value of which is indicated by the movement over a dial (Z of a pointer (1 geared to the shaft (Z Spotting corrections can be recorded by a pointer (Z which is frictionally connected to the pointer d.

It is known that when lateral deflection is applied to a gun sight in the plane of the sight, the sight line is depressed as a result, this depression being known as the complementary error. The amount of this depression is equal to the amount of the aforesaid correcting factor.

2 Y sin 0: cos a R XTX sin 04 cos oz,

represented by the movement of the aforesaid slider H. In order to introduce this correcting factor, the slider H has a rack member k which meshes with rack teeth on the vertical deflection dial (Z8 (or on a member connected to this dial) so that the zero mark on this dial is displaced from its normal position by an amount proportionate to the value of the said correcting factor.

The aforesaid factor 1) i (Y S111 Oi cos 0!) is a close approximation to the correct expresslon, but 1f further accuracy is required, the factor would be expressed sin D tan 04?) sin (aid) cos (aid) and furthermore if mathematical accuracy is required, the said factor would be expressed sin D tan sin a cos (a A: (Z)

in either case the mechanism would be modified accordingly.

Referring now to the training or lateral deflection portion of the apparatus, the training handle 0 is geared to a roller 0 which therefore rotates at a speed proportionate to R This roller forms the primary element of a variable speed device of which the secondary element is constituted by a disc 0 and the interposed adjustable element is constituted by balls mounted in a carrier 0 In the example shown the disc 0 also serves as the primary element of a second variable speed device the secondary element of which is constituted by a roller 0* and the interposed adjustable element is constituted by balls mounted in a carrier 0 The carrier 0 is connected by a rod 0 to one arm (1 of a bell-crank lever the other arm C of which has a slot to receive a. pin 0 on a block 0 through which the links C C can slide at right angles to each other. The link C is interposed between two parallel and equal pivoted arms C and C of which the former is operated from the aforesaid shaft (Z in accordance with the factor (aid). The spindle of the arm C may be common to the aforesaid arm B moved inaccordance with this factor. The link C is interposed between two parallel and equal pivoted arms C 0 of which the former is driven from one of the shafts 0: so that the said arm rocks in accordance with the value of on. This arrangement constitutes a linkage (indicated generally by the reference letter C for dividing a factor proportionate to the movement of the link C by a factor proportionate to the lateral movement of the link C* and giving to the rod 0 a movement proportionate to the quotient. As the link C receives from the arm C a lateral movement proportionate to cos (aid) and the link C receives from the arm C a lateral movement proportionate to cos a, it follows that the carrier 0 is displaced by an amount proportionate to the factor cos (a i d) cos a and consequently the speed of rotation of the disc 0 is proportionate to with the result that the roller 0* is caused to rotate at a speed proportionate to sin (a :l: (i) sin a COS Oi COS (a :l: d)

and the pointer C which is geared to the said roller consequently also rotates at a speed proportionate to this factor. The pointer D is geared to a roller D constituting the secondary element of a variable speed device the primary element of which is constituted by a disc D driven by the same constant speed motor that drives the aforesaid disc (W, and the interposed adjustable element is constituted by balls mounted in a carrier D If therefore the latter carrier be so adjusted that the speed of rotation of the pointer D is equal to the speed of rotation of the pointer C then the travel of the said carrier, being proportionate to this speed, is a measure of the last-mentioned factor. In order to introduce the value of this factor, the carrier D is connected by a rod D to a pivoted slotted arm D by a pin and slot connection forming part of a multiplying linkage (indicated generally at D) the other elements of which comprise a slotted extension 6 of the aforesaid time bar 6 and a slotted slider D operated by a screw-threaded shaft D which is geared to the aforesaid shaft D*. The slots in the said extension and slider are arranged at right angles to each other and the slider is constrained to move in a path at right angles to the path of the bar 6. A pin on a block slidably mounted on the arm D passes through the slots in the members D and 6 As the arm D moves in an angle whose sine is the factor last referred to and the extension 6 moves in accordance with the factor T, it follow-s that the movement of the slider D is proportionate to sin (a i d) sin a cos 0! cos (a d: d)

which from Formula (2) is seen to be equal to sin D. Consequently the rotation of the shaft D in causing the pointer D to travel R X TX at the same rate as the pointer C is propor tionate to sin D. This shaft is screw-threaded to operate a nut carrying a pointer D arranged contiguous to a chart D provided with suitable curves from which the right and left deflection in the plane of the sight can be read, this chart being operated by one of the shafts a rotating in accordance with the angle of sight on. The said nut carries a screw-threaded sleeve D which is slidably keyed to a shaft D and operates a pointer D by which spotting corrections can be made. The conversion from horizontal deflection into deflection in the plane of the line of sight, instead of being effected by the chart D, may be effected by a suitable linkage, a three-dimensional cam or other convenient means.

In operation the elevating number and the training number turn the handles b and c in order to maintain the horizontal and vertical cross-lines of the respective telescopes A and A on the target and in so doing rotate the pointers B and C as aforesaid. The vertical deflection rate-following number operates the handle cl until the pointer (Z moves at the same rate as the pointer B and the lateral deflection rate-following number operates the handle D until the pointer D moves at the same rate as the pointer C The Height and fuze number, having previously been given the height of the target as obtained from a height-finder, rotates the handle E so as to maintain the pointer E on the height curve on the chart E corresponding to the particular height of the target. The vertical deflection and the lateral deflection are called out by the respective rate-following numbers and the number of the fuze is ascertained by the height and fuze number from the fuze curves on the chart E and is called out. The point at which the projectile bursts is noted and any spotting corrections necessary may be effected by operating the pointers (Z and D.

Instead of pairs of pointers B (Z and C D a single balanced pointer operated through an epicyclic gear may, if desired, be employed in place of either or each such pair of pointers, or one pointer of each pair may be replaced by a graduated dial.

The lateral deflection may be automatically given either in the plane of sight as above described or in the horizontal plane (in which case the rack member 7& would not be provided and the chart D would be replaced by a plain stationary dial and rotating pointer) according to the type of sight fitted to the guns and the method of applying deflections thereto. Furthermore the deflections may be transmitted direct to the guns, this transmission being additional to, or in substitution for, indicating them as hereinbefore described.

Wind and ballistic corrections, tangent elevation and other settings may also be embodied in the apparatus, and allowance may be made for the lost time between the setting of the shell fuze and the departure of the shell from the gun.

Instead of the linkages l3 and C", herein described, logarithmic devices, three dimensional cams or a system of variable speed devices may be employed, and instead of the linkages (Z D and F three dimensional cams or a system of variable speed devices may be employed.

The herein described apparatus owes its accuracy to the fact that it operates in strict accordance with mathematical formulae expressing the relationship between the angular rates at the moment of observation and the future position of the target. The interpretation of the formulae is effected wholly by mechanical means, thus avoiding the disadvantages inseparable from electrical devices which are necessarily of delicate construction and are easily influenced by climatic conditions. Further the fact of having to make electrical connections is in itself a potential source of delay and error and in the event of any part of the instrument not functioning properly the reason thereof cannot be so easily detected as in a mechanical apparatus.

hat I claim and desire to secure by Let ters Patent of the United States is 1. Apparatus for use. in the fire control of anti-aircraft guns, comprising an observing sight, a member connected to said sight and movable therewith in accordance with a rate of elevation necessary to keep the line of sight on the moving aerial target, a member associated with and adapted to be moved at the same rate as said former member, infinitely variable speed devices for driving said members, means controlling said devices, and means associated with said lattermember for indicating vertical deflection tot-he guns.

2. Apparatus for use in the fire control of anti-aircraft guns, comprising an observing sight, a member connected to said sight and movable substantially therewith in accordance with a rate of training necessary to keep the line of sight on the moving aerial target, a. member associated with and adapted to be moved at the same rate as said former member, infinitely variable speed devices for driving said members, means controlling said devices, and means associated with said latter member for indicating horizontal deflection tothe guns.

3. Apparatus for use in the fire control of anti-aircraft guns, comprising an observing sight, two members connected to said sight and movable substantially therewith respectively in accordance with the elevation and train rate necessaryto keep the line of sight on the moving aerial target, two corresponding members associated with and adapted to be moved at the same rate as said former members, infinitely variable speed devices for driving said members, means controlling said devices, and means associated with said latter members for indicating vertical and horizontal deflection to the guns.

4. Apparatus for use in the fire control of anti-aircraft guns, comprising an observing sight, a member connected to said sight and movable therewith in accordance with a rate of elevation necessary to keep the line of sight on the moving aerial tar-get, means for modifying said rate in accordance with certain corrections, a member associated with and adapted to be moved at the same rate as said former member, infinitely variable speed devices for driving said members, means controlling said devices, and means associated with said latter member, for indicating vertical deflection to the guns.

5. Apparatus for use in the fire control of anti-aircraft guns, comprising an observing sight, a member connected to said sight and movable therewith in accordance with a rate of training necessary to keep the line of sight on the moving aerial target, means for modifying said rate in accordance with certain corrections, a member associated with and adapted to be moved at the same rate as said former member, infinitely variable speed devices for driving said members, means controlling said devices, and means associated with said latter member, for indicating horizontal deflection to the guns.

6. Apparatus for use in the fire control of anti-aircraft guns, comprising an observing sight, two members connected to said sight and movable therewith respectively in accordance with the elevation and train rate necessary to keep the line of sight on the moving aerial target, means for modifying said rate in accordance with certain corrections, two corresponding members associated with and adapted to be moved at the same rate as said former members, infinitely variable speed devices for driving said members, means controlling said devices, and means associated with said latter members for indicating vertical and horizontal deflection to the guns.

7. Apparatus for use in the fire control of anti-aircraft guns, comprising an observing sight, two pointers connected to said sight and movable therewith respectively in accordance with the elevation and train rate necessary to keep the line of sight on the moving aerial target, other pointers associated with and adapted to be moved at the same rate as said former pointers, infinitely variable speed devices for actuating said latter pointers, adjustable mechanisms for actuating the speed varying elements of one of said devices, a member operable in accordance with the time of flight of the projectile for operating one of said mechanisms, and other members operable in accordance with the vertical and horizontal deflection to be ascertained for operating said other mechanisms,

whereby said latter pointers are moved at the same rate as said former pointers for indicating the deflection to the guns.

8. In apparatus for the fire control of antiaircraft guns, the combination of an observing instrument, members movable in accordance with the rate of motion necessary to keep said instrument on the target, secondary coacting members governed by corrective mechanism and actuated through variable speed mechanism to move at the same rate as the former members, and means associated with said secondary member for indicating the resultant deflection values at the guns.

9. In apparatus for the fire control of antiaircraft guns, the combination of observing sights, primary members respectively movable in accordance with the rate of elevation and training necessary to keep said sights on the moving target, and severally coacting secondary members driven by variable speed mechanism adjusted in accordance with corrections so as to move at the same rate as said primary members, and means driven in accordance with the movement of the said secondary member to indicate elevation and training deflections to the guns.

10. In apparatus for the fire control of antia-ircraft guns, the combination of members for respectively indicating training and elevation angles for the guns, differential motion mechanism for actuating said members, means for actuating a portion of said mechanisms in accordance with the rate of movement of said target, and means including variable speed mechanism for actuating said mechanism in accordance with deflection corrections.

11. In apparatus for the fire control of antiaircraft guns, the combination of members respectively movable in accordance with the rate of movement of the target to indicate elevation and training angles, means severally co-acting with said members for indicating horizontal and vertical deflection, variable speed mechanism adjustable in accordance with the time of flight of the projectile for governing said means, and means associated with said first named means for indicating fuse-setting data.

12. Apparatus for use in the fire control of anti-aircraft guns, comprising in combination an observing sight or its equivalent, two movable members, means for moving one of said members in moving said sight in elevation to keep iton the moving aerial target, a variable speed device driving the second movable member, an actuating member for moving the adjustable speed varying element of said variable speed device so as to cause the second movable member to move at the same rate as the first movable member, an element moved in accordance with the time of flight of the shell, and means for multiplying the displacements of the speed varying element and the element moved in accordance with the time of flight of the shell, said multiplying means being situated between said actuating member and said speed varying element whereby when said movable members are moving at the same rate the position of the actuating member is a measure of the vertical deflection for a given time of flight of the shell.

18. Apparatus for use in the fire control of anti-aircraft guns, comprising in combination an observing sight or its equivalent, two movable members, means for moving one of said members in moving said sight in elevation to keep it on the moving aerial target, means for automatically varying the position of the latter member in accordance with a factor involved in the determination of the vertical deflection, a variable speed device driving the second movable member, an actuating member for moving the adjustable speed varying element of said variable speed device so as to cause the second movable member to move at the same rate as the first movable member, an element moved in accordance with the time of flight of the shell, and means for multiplying the displacements of the speed varying element and the element moved in accordance with the time of flight of the shell, said multiplying means being situated between said actuating member and said speed varying element whereby when said movable members are moving at the same rate the position of the actuating member is a measure of the vertical deflection for a given time of flight of the shell.

14. Apparatus for use in the fire control of anti-aircraft guns, comprising in combination an observing sight or its equivalent, two movable members, means for moving one of said members in moving said sight in training to keep it on the moving aerial target, a variable speed device driving the said mov able member, an actuating member for moving the adjustable speed varying element of said variable speed device so as to cause the second movable member to move at the same rate as the first movable member, an element moved in accordance with the time of flight of the shell, and means for multiplying the displacements of the speed varying element and the element moved in accordance with the time of flight of the shell, said multiplying means being situated between said actuating member and said speed varying element whereby when said movable members are moving at the same rate the position of the actuating member is a measure of the horizontal deflection for a given time of flight of the shell.

15. Apparatus for use in the fire control of anti-aircraft guns, comprising in combination an observing sight or its equivalent, two movable members, means for moving one of said members in moving said sight in training to keep it on the moving aerial target, means for automatically varying the position of the latter member in accordance with a factor involved in the determination of the horizontal deflection, a variable speed device driving the second movable member, an actuating member for moving the adjustable speed varying element of said variable speed device so as to cause the second movable member to move at the same rate as the first movable member, an element moved in accordance with the time of flight of the shell, and means for multiplying the displacements of the speed varying element and the element moved in accordance with the time of flight of the shell, said multiplying means being situated between said actuating member and said speed varying element whereby when said movable members are moving at the same rate the position of the actuating member is a measure of the horizontal deflection for a given time of flight of the shell.

16. Apparatusfor use in the fire control of anti-aircraft guns, comprising in combination an observing sight or its equivalent, a pair of movable members, means for moving one member of said pair in moving said sight in elevation to keep it on the moving aerial target, a Variable speed device driving the second movable member, an actuating member for moving the adjustable speed varying element of said variable speed device so as to cause the second movable member to move at the same rate as the first movable member, an element mvoed in accordance with the time of flight of the shell, means for multiplying the displacements of the speed varying element and the element moved in accordance with the time of flight of the shell, said-multiplying means being situated between said actuating member and said speed varying element whereby when said movable members are moving at the same rate the position of the actuating member is a measure of the vertical deflection for a given time of flight of the shell, a second pair of movable members, means for moving one member of said second pair in moving said sight in training to keep it on the moving aerial target, a variable speed device driving the other member of said second pair, an actuating member for moving the adjustable speed varying element of the second variable speed device so as to cause the last mentioned movable member to move at the same rate as the first movable member of the second pair of movable members, and means for multiplying the displacement of said second speed varying element and said element moved in accordance with the time of flight, the latter multiplying means being situated between the second actuating member and the second speed varying element whereby when said second pair of movable members are moving at the same rate the position of the second actuating member is a measure of the horizontal deflection for a given time of flight of the shell.

17. Apparatus for use in the fire control of anti-aircraft guns, comprising in combination an observing sight or its equivalent, a pair of movable members, means for moving one member of said pair in moving said sight in elevation to keep it on the moving aerial target, means for automatically varying the position of the latter member in accordance with a factor involved in the determination of the vertical deflection, a variable speed device driving the second movable member, an actuating member for moving the adjustable speed varying element of said variable speed device so as to cause the second movable member to move at the same rate as the first movable member, an element moved in accordance with the time of flight of the shell, means for multiplying the displacements of the speed varying element and the element moved in accordance with the time of flight of the shell, said multiplying means being situated between said actuating member and said speed varying element whereby when said movable members are moving at the same rate the position of the actuating member is a measure of the vertical deflection for a given time of flight of the shell, a second pair of movable members, means for moving one member of said second pair in moving said sight in training to keep it on the moving aerial target, means for automatically varying the position of the latter member in accordance with factors involved in determining the vertical and horizontal deflections, a variable speed device driving the other member of said second pair, an actuating member for moving the adjustable speed varying element of the second variable speed device so as to cause the last mentioned movable member to move at the same rate as the first movable member of the second pair of movable members, and means for multiplying the displacements of said second speed varying element and said element moved in accordance with the time of flight, the latter multiplying means being situated between the second actuating member and the second speed varying element whereby when said second pair of movable members are moving at the same rate the position of the second actuating member is a measure of the horizontal deflect-ion for a given time of flight of the shell.

18. In apparatus for determining the deflection of a moving aerial target for use in the fire control of anti-aircraft guns comprising in combination a sight, means for moving the sight to keep the target in the field of view, a member actuated in accordance with the movements of the sights, and mechanism for introducing deflection corrections in accordance with a predetermined mathematical factor, said mechanism including a second member c-o-acting with the first named member and a linkage device for controlling the last named member.

19. In apparatus for determining the deflection of a moving aerial target for use in the fire control of anti-aircraft guns comprising in combination a sight, means for moving the sight to keep the target in the field of view, a member actuated in accordance With the movements of the sight and mechanism for introducing deflection corrections, said mechanism including an infinitely variable speed device a second member co-acting With the first named member, and a linkage device for controlling the last named member.

20. In apparatus for determiningthe horizontal deflection of a moving aerial target for use in the fire control of anti-aircraft guns comprising in combination a sight, means for moving the sight to keep the target in the field of View, a member actuated in accordance with the movements of the sight, and mechanism for introducing horizontal deflection corrections in accordance with the hereinbefore defined factor Sill (a :l: d) sin (1 cos a cos (aid) sin (a i: d) sin a sin (a i (1) Sin a COS 0t (aid) respectively, said mechanism including second members severally co-acting with the first named members, and linkage devices for controlling the last named members.

PERCY WILLIS GRAY.

and 

